Class: Shell (Ruby 2.3.4)

Shell

Shell implements an idiomatic Ruby interface for common UNIX shell commands.

It provides users the ability to execute commands with filters and pipes, like sh/csh by using native facilities of Ruby.

Examples ↑

Temp file creation ↑

In this example we will create three tmpFile‘s in three different folders under the /tmp directory.

sh = Shell.cd("/tmp") # Change to the /tmp directory
sh.mkdir "shell-test-1" unless sh.exists?("shell-test-1")
# make the 'shell-test-1' directory if it doesn't already exist
sh.cd("shell-test-1") # Change to the /tmp/shell-test-1 directory
for dir in ["dir1", "dir3", "dir5"]
  if !sh.exists?(dir)
    sh.mkdir dir # make dir if it doesn't already exist
    sh.cd(dir) do
      # change to the `dir` directory
      f = sh.open("tmpFile", "w") # open a new file in write mode
      f.print "TEST\n"            # write to the file
      f.close                     # close the file handler
    end
    print sh.pwd                  # output the process working directory
  end
end

Temp file creation with self ↑

This example is identical to the first, except we’re using Shell::CommandProcessor#transact.

Shell::CommandProcessor#transact executes the given block against self, in this case sh; our Shell object. Within the block we can substitute sh.cd to cd, because the scope within the block uses sh already.

sh = Shell.cd("/tmp")
sh.transact do
  mkdir "shell-test-1" unless exists?("shell-test-1")
  cd("shell-test-1")
  for dir in ["dir1", "dir3", "dir5"]
    if !exists?(dir)
      mkdir dir
      cd(dir) do
        f = open("tmpFile", "w")
        f.print "TEST\n"
        f.close
      end
      print pwd
    end
  end
end

Pipe /etc/printcap into a file ↑

In this example we will read the operating system file /etc/printcap, generated by cupsd, and then output it to a new file relative to the pwd of sh.

sh = Shell.new
sh.cat("/etc/printcap") | sh.tee("tee1") > "tee2"
(sh.cat < "/etc/printcap") | sh.tee("tee11") > "tee12"
sh.cat("/etc/printcap") | sh.tee("tee1") >> "tee2"
(sh.cat < "/etc/printcap") | sh.tee("tee11") >> "tee12"

Attributes

cascade[RW]
debug[RW]
debug?[RW]
verbose[RW]
verbose?[RW]
command_processor[R]
cwd[R]

Returns the current working directory.

debug[RW]
debug?[RW]
dir[R]

Returns the current working directory.

dir_stack[R]
dirs[R]
getwd[R]

Returns the current working directory.

process_controller[R]
pwd[R]

Returns the current working directory.

record_separator[RW]
system_path[R]

Returns the command search path in an array

umask[RW]

Returns the umask

verbose[RW]
verbose?[RW]

Public Class Methods

alias_command(alias, command, *opts, &block)

Convenience method for Shell::CommandProcessor.alias_command. Defines an instance method which will execute a command under an alternative name.

Shell.def_system_command('date')
Shell.alias_command('date_in_utc', 'date', '-u')
Shell.new.date_in_utc # => Sat Jan 25 16:59:57 UTC 2014

 
               # File shell.rb, line 392
def Shell.alias_command(ali, command, *opts, &block)
  CommandProcessor.alias_command(ali, command, *opts, &block)
end
cd(path)

Creates a new Shell instance with the current working directory set to path.

 
               # File shell.rb, line 125
def cd(path)
  new(path)
end
debug=(val) 
 
               # File shell.rb, line 114
def debug=(val)
  @debug = val
  @verbose = val if val
end
def_system_command(command, path = command)

Convenience method for Shell::CommandProcessor.def_system_command. Defines an instance method which will execute the given shell command. If the executable is not in ::default_system_path, you must supply the path to it.

Shell.def_system_command('hostname')
Shell.new.hostname # => localhost

# How to use an executable that's not in the default path

Shell.def_system_command('run_my_program', "~/hello")
Shell.new.run_my_program # prints "Hello from a C program!"

 
               # File shell.rb, line 372
def Shell.def_system_command(command, path = command)
  CommandProcessor.def_system_command(command, path)
end
default_record_separator() 
 
               # File shell.rb, line 158
def default_record_separator
  if @default_record_separator
    @default_record_separator
  else
    $/
  end
end
default_record_separator=(rs) 
 
               # File shell.rb, line 166
def default_record_separator=(rs)
  @default_record_separator = rs
end
default_system_path()

Returns the directories in the current shell’s PATH environment variable as an array of directory names. This sets the #system_path for all instances of Shell.

Example: If in your current shell, you did:

$ echo $PATH
/usr/bin:/bin:/usr/local/bin

Running this method in the above shell would then return:

["/usr/bin", "/bin", "/usr/local/bin"]

 
               # File shell.rb, line 142
def default_system_path
  if @default_system_path
    @default_system_path
  else
    ENV["PATH"].split(":")
  end
end
default_system_path=(path)

Sets the #system_path that new instances of Shell should have as their initial system_path.

path should be an array of directory name strings.

 
               # File shell.rb, line 154
def default_system_path=(path)
  @default_system_path = path
end
install_system_commands(pre = "sys_")

Convenience method for Shell::CommandProcessor.install_system_commands. Defines instance methods representing all the executable files found in ::default_system_path, with the given prefix prepended to their names.

Shell.install_system_commands
Shell.new.sys_echo("hello") # => hello

 
               # File shell.rb, line 412
def Shell.install_system_commands(pre = "sys_")
  CommandProcessor.install_system_commands(pre)
end
new(pwd, umask) → obj

Creates a Shell object which current directory is set to the process current directory, unless otherwise specified by the pwd argument.

 
               # File shell.rb, line 183
def initialize(pwd = Dir.pwd, umask = nil)
  @cwd = File.expand_path(pwd)
  @dir_stack = []
  @umask = umask

  @system_path = Shell.default_system_path
  @record_separator = Shell.default_record_separator

  @command_processor = CommandProcessor.new(self)
  @process_controller = ProcessController.new(self)

  @verbose = Shell.verbose
  @debug = Shell.debug
end
notify(*opts) 
 
               # File shell.rb, line 425
def self.notify(*opts)
  Shell::debug_output_synchronize do
    if opts[-1].kind_of?(String)
      yorn = verbose?
    else
      yorn = opts.pop
    end
    return unless yorn

    if @debug_display_thread_id
      if @debug_display_process_id
        prefix = "shell(##{Process.pid}:#{Thread.current.to_s.sub("Thread", "Th")}): "
      else
        prefix = "shell(#{Thread.current.to_s.sub("Thread", "Th")}): "
      end
    else
      prefix = "shell: "
    end
    _head = true
    STDERR.print opts.collect{|mes|
      mes = mes.dup
      yield mes if iterator?
      if _head
        _head = false
        prefix + mes
      else
        " "* prefix.size + mes
      end
    }.join("\n")+"\n"
  end
end
unalias_command(ali)

Convenience method for Shell::CommandProcessor.unalias_command

 
               # File shell.rb, line 397
def Shell.unalias_command(ali)
  CommandProcessor.unalias_command(ali)
end
undef_system_command(command)

Convenience method for Shell::CommandProcessor.undef_system_command

 
               # File shell.rb, line 377
def Shell.undef_system_command(command)
  CommandProcessor.undef_system_command(command)
end

Public Instance Methods

cd(path = nil, verbose = @verbose)
Alias for: chdir
chdir(path)

Creates a Shell object which current directory is set to path.

If a block is given, it restores the current directory when the block ends.

If called as iterator, it restores the current directory when the block ends.

 
               # File shell.rb, line 260
def chdir(path = nil, verbose = @verbose)
  check_point

  if iterator?
    notify("chdir(with block) #{path}") if verbose
    cwd_old = @cwd
    begin
      chdir(path, nil)
      yield
    ensure
      chdir(cwd_old, nil)
    end
  else
    notify("chdir #{path}") if verbose
    path = "~" unless path
    @cwd = expand_path(path)
    notify "current dir: #{@cwd}"
    rehash
    Void.new(self)
  end
end
Also aliased as: cd
debug=(val) 
 
               # File shell.rb, line 215
def debug=(val)
  @debug = val
  @verbose = val if val
end
expand_path(path) 
 
               # File shell.rb, line 226
def expand_path(path)
  File.expand_path(path, @cwd)
end
inspect() 
 
               # File shell.rb, line 417
def inspect
  if debug.kind_of?(Integer) && debug > 2
    super
  else
    to_s
  end
end
jobs()

Returns a list of scheduled jobs.

 
               # File shell.rb, line 344
def jobs
  @process_controller.jobs
end
kill(signal, job)

Sends the given signal to the given job

 
               # File shell.rb, line 352
def kill(sig, command)
  @process_controller.kill_job(sig, command)
end
popd()
Alias for: popdir
popdir()

Pops a directory from the directory stack, and sets the current directory to it.

 
               # File shell.rb, line 328
def popdir
  check_point

  notify("popdir")
  if pop = @dir_stack.pop
    chdir pop
    notify "dir stack: [#{@dir_stack.join ', '}]"
    self
  else
    Shell.Fail DirStackEmpty
  end
  Void.new(self)
end
Also aliased as: popd
pushd(path = nil, verbose = @verbose)
Alias for: pushdir
pushdir(path)
pushdir(path) { &block }

Pushes the current directory to the directory stack, changing the current directory to path.

If path is omitted, it exchanges its current directory and the top of its directory stack.

If a block is given, it restores the current directory when the block ends.

 
               # File shell.rb, line 294
def pushdir(path = nil, verbose = @verbose)
  check_point

  if iterator?
    notify("pushdir(with block) #{path}") if verbose
    pushdir(path, nil)
    begin
      yield
    ensure
      popdir
    end
  elsif path
    notify("pushdir #{path}") if verbose
    @dir_stack.push @cwd
    chdir(path, nil)
    notify "dir stack: [#{@dir_stack.join ', '}]"
    self
  else
    notify("pushdir") if verbose
    if pop = @dir_stack.pop
      @dir_stack.push @cwd
      chdir pop
      notify "dir stack: [#{@dir_stack.join ', '}]"
      self
    else
      Shell.Fail DirStackEmpty
    end
  end
  Void.new(self)
end
Also aliased as: pushd
system_path=(path)

Sets the system path (the Shell instance’s PATH environment variable).

path should be an array of directory name strings.

 
               # File shell.rb, line 204
def system_path=(path)
  @system_path = path
  rehash
end